1. Field of the Invention
The present invention relates to an apparatus and method for cooling systems of an internal combustion engine, and more particularly to an anode device and maintenance method for marine engines.
2. Brief Description of the Related Art
Many marine engines have a cooling system which involves the introduction of seawater through the heat exchanger engine or manifolds. The engine cooling system generally has one or more threaded openings that are designed to receive a sacrificial zinc anode and plug. These zinc pencils or pencil anodes as they are often referred to, contain a zinc alloy and usually are supplied with threaded brass plugs. The threaded brass plugs are threaded externally to fit within the threaded opening of the engine cooling system port. The brass plugs also contain internal threads for threading with the zinc anode so that the zinc anode is held within the brass plug. The brass fitting with the zinc anode typically threads into a port of an engine or cooling system so that the anode comes into contact with the raw seawater passing through the system. The zinc anode has a useful life and requires replacement. The replacement of the zinc anode is done to extend the life of marine engine coolant systems, such as, engines, heat exchangers, pipes, condensers, water cooling jackets, and other components that come into contact with the seawater.
The function of the zinc anode is to reduce corrosion of other components. For example, when two different metals are in contact, electrons will flow from the more negatively charged metal (anode) to the more positive metal (cathode). For example, in cooling systems, dissimilar metals may be in contact through a fluid (e.g., seawater) which acts as an electrolyte. A current may be established which promotes galvanic corrosion. In situations where the metals (e.g., the two different metals) are to be protected from corrosion, an additional metal is introduced so it is available to serve as the anode for both of the other metals (i.e., the metals that are desired to be preserved). The zinc anode is used, and is commonly termed the sacrificial anode, because it is designed to protect the engine cooling system components from degradation due to galvanic corrosion. Providing the sacrificial zinc anode in the form of a plug which is sacrificed as an anode directs this electrolysis to a relatively inexpensive, replaceable component in order to protect the more valuable cooling system or engine components. The zinc anode degrades upon use, and is replaceable, which is much less costly than replacing other, more expensive components of the cooling system. It is possible that other types of metals may be used in alloys with, or as a substitute for zinc, but zinc is a widely used sacrificial anode.
One of the problems encountered in the replacement of the zinc anode is that the plug containing the zinc anode generally seals an access port to the flow path of the cooling system where the coolant (seawater) passes. Due to the configurations of the cooling systems, there often is seawater present in the cooling system, which emerges from the cooling system when the plug is removed. Even slowly removing the brass plug containing the zinc anode (or a spent zinc anode that is to be replaced), may result in spray or leakage of seawater out of the cooling system and onto surrounding components. The escape of seawater from the cooling system may contaminate or corrode other nearby components, such as, for example, an alternator or starter. In addition, the escaping seawater may build up in the bilge, which then often must be pumped out and rinsed with fresh water. Another problem is that the brass fitting containing the zinc may be difficult to withdraw from the port. In some cases the threads may become stuck, and attempts to remove the brass fitting and the remainder of the spent zinc anode that may be attached to the fitting, may result in pieces of the anode fragmenting off into the cooling system. In some instances, the zinc anode may fall into the engine system and block the passage of the seawater. This could cause engine overheating and potential destruction of the engine and associated components.
At times, when the maintenance of the zinc anode is not performed in a timely manner, the zinc can corrode away to the point that it cannot be removed from the plug. This requires both a new plug and new anode to be installed.
A need exists for a device and method that will facilitate maintenance and installation of a zinc anode in an economical manner without the drawbacks of the prior plugs and methods, particularly the escape of water from the cooling system.